Roughly 45 million people in the US are afflicted by the skin condition acne vulgaris. It is associated with lesions on the skin that are unsightly but can also be painful and leave scars.
The exact etiology of acne remains controversial. Keratinous material initially plugs the duct of a sebaceous gland. Sebum is produced and trapped, thereby enlarging the gland. The propionibacterium acnes (P. acnes) bacterium, which is a normal part of the skin flora, propagates in the gland due to the sebum buildup. These bacteria are inflammatory and may lead to the formation of the acne pustules.
Treatments typically include topical and systemic therapies. Topical treatments are aimed at removing follicular plugs and cleaning the sebaceous glands. These treatments are useful in treating some minor forms of acne. Oral treatments include antibiotics to suppress the growth of P. acnes. However, these treatments have side effects typical of these drugs, such as skin dryness, digestive problems, and the development of antibiotic resistant bacteria.
It is known that the P. acnes bacteria produce porphyrins. The particular porphyrin typically produced by P. acnes has a peak in absorption at 415 nanometers. Although red light is absorbed less, the light penetrates the skin deeper than other light. Thus, devices often include 660 nanometer light as well. Also, red light has an anti-inflammatory effect on tissue and may therefore aid in improving healing of pustules.
More recently, the use of both blue light (e.g., 415 nm) and red light (e.g., 660 nm) in the treatment of acne has been described. These lights can be applied with and without photo enhancers. These devices typically require high energy light sources to limit the treatment time to a period that is acceptable for a person to sit still. For example, the light sources tend to be high energy fluorescent bulbs and LEDs.